|Publication number||US6945118 B2|
|Application number||US 10/758,745|
|Publication date||Sep 20, 2005|
|Filing date||Jan 13, 2004|
|Priority date||Jan 13, 2004|
|Also published as||CN1938571A, EP1709410A2, US20050150303, WO2005071376A2, WO2005071376A3|
|Publication number||10758745, 758745, US 6945118 B2, US 6945118B2, US-B2-6945118, US6945118 B2, US6945118B2|
|Inventors||William D. Maitland, Jr., Louis J. Panagotopulos, Zlatko Uvanovic|
|Original Assignee||Honeywell International Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (10), Referenced by (28), Classifications (5), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Embodiments are generally related to sensing devices and methods thereof. Embodiments are also related to pressure transducers. Embodiments are additionally related to pressure sensors. Embodiments are additionally related to ceramic-on-metal and ATF (Advanced Thick Film) processes and techniques.
Various sensors are known in the pressure sensing arts. Pressure transducers are well known in the art. One example of a pressure transducer is a device formed with a silicon substrate and an epitaxial layer, which is grown on the substrate. A portion of the substrate can then be removed, leaving a thin, flexible diaphragm portion. Sensing components can be located in the diaphragm portion to form a pressure transducer. In operation, at least one surface of the diaphragm can be exposed to a process pressure. The diaphragm deflects according to the magnitude of the pressure, and this deflection bends the attached sensing components. Bending of the diaphragm creates a change in the resistance value of the sensing components, which can be reflected as a change in the output voltage signal of a resistive bridge formed at least partially by the sensing components.
Some techniques for forming a composite diaphragm for a pressure transducer or similar device involve configuring a substrate layer having a first conductivity type, wherein the substrate layer includes a first surface. Positive implants can then be deposited in the first surface of the substrate layer, and an epitaxial layer grown on the first surface of the substrate layer so that the positive implants form positive diffusions in the epitaxial layer. An oxide pattern can be then formed on the epitaxial layer, and a top layer deposited over the epitaxial layer and oxide pattern. The substrate layer and positive diffusions of the epitaxial layer can then be etched to form the composite diaphragm. Such a composite diaphragm can therefore be provided for use in a pressure sensor or like device. The diaphragm comprises a first layer of silicon nitride and a second layer attached to the silicon nitride layer and comprising a pressure sensor pattern of silicon material.
Pressure transducers of the type which comprise a thin, relatively flexible diaphragm portion of suitable material, such as silicon or ceramic, on which either a selected resistive element or a capacitive plate is printed whereby exposure to a pressure source causes deflection of the diaphragm will cause a change in the resistive value of the resistive element or a change in the spacing of the capacitive plate with a mating capacitive plate and concomitantly a change in capacitance are therefore well known in the art.
When used as a low pressure sensor, economical packaging of the transducer in a housing so that an effective seal is obtained while at the same time preventing stress related to the mounting and sealing of the transducer from influencing the output becomes problematic. This is caused, at least in part, by the significant difference in thermal expansion between the material used to form the transducer, e.g., silicon, ceramic or the like, and the housing of plastic or the like. A conventional sealing arrangement involves placement of a ring of sealing material around an inlet pressure port in a housing and mounting the transducer so that the pressure sensitive diaphragm is precisely aligned with the pressure port. This conventional arrangement not only involves stress isolation issues, it also limits flexibility in design choices in defining the location of the transducer within the package.
One of the major problems with such pressure transducer devices, including those that utilize diaphragm or diaphragm portion configurations, is that such devices are not reliable in corrosive and high-temperature applications. A need therefore exists for a low-cost high accuracy pressure transducer that can be used in corrosive media and high-temperature applications.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
It is, therefore, one aspect of the present invention is to provide an apparatus and a method which overcomes the above noted prior art limitations.
It another aspect of the present invention to provide an improved sensor apparatus and method.
It is an additional aspect of the present invention to provide for an improved transducer apparatus.
It is yet an additional aspect of the present invention to provide for an improved transducer apparatus, which can be formed utilizing ceramic-on-metal and ATF (Advanced Thick Film) processes and techniques.
It is a further aspect of the present invention to provide for an improved method for connecting the flex circuit to the bridge circuit.
The aforementioned aspects of the invention and other objectives and advantages can now be achieved as described herein. A transducer apparatus is disclosed herein, including a method thereof for forming the transducer apparatus. A metal diaphragm is molecularly bonded to a ceramic material to form a ceramic surface thereof. A bridge circuit is connected to the ceramic surface of the metal diaphragm. An input pressure port for pressure sensing thereof can then be provided, wherein the input pressure port is connected to the metal diaphragm to thereby form a transducer apparatus comprising the metal diaphragm, the bridge circuit and the input pressure port.
The metal diaphragm is preferably welded to the input pressure port. The metal diaphragm and the ceramic surface thereof preferably operate over a temperature of range of at least approximately −40° C. to 150° C., as does the transducer apparatus. The ceramic material is molecularly bonded to the metal diaphragm to form the ceramic surface thereof. The ceramic surface bonded to the metal diaphragm can also be configured as a ceramic substrate. The ceramic surface provides corrosion protection to the metal diaphragm. The bridge circuit generally comprises a resistor network and provides an output proportional to the applied force. A flex circuit comprising an ASIC (Application Specific Integrated Circuit), associated circuitry and EMI protection provides signal conditioning, calibration and compensation. A snap on connector system comprising a plastic snap on lead frame and Z axis conductor material can be utilized for connecting the flex circuit to the bridge network which is located on the diaphragm.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment of the present invention and are not intended to limit the scope of the invention.
The flex strip 112 connects the bridge circuit 115 to a case or housing 108 (e.g., a cover) and a connector portion 106. The flex circuit can be electrically and mechanically attached to the bridge circuit by catching the flex circuit 112 and z-axis conductor 128 with a plastic lead frame 127 which snaps around the and holds the z axis conductor and flex circuit in place. The components can be aligned such that the conductor path is from the bridge circuit, through the z axis conductor into the flex circuit. Such an assembly method and configuration can therefore eliminate the need for soldering and wire bonding.
An input pressure port 122 can be provided for pressure sensing thereof, such that the input pressure port is welded to the metal diaphragm 119 to thereby form the transducer apparatus 100 comprising the metal diaphragm, the ceramic substrate the bridge circuit and the input pressure port.
Transducer apparatus 100 solves the need for a low-cost and high-accuracy pressure transducer that can be utilized in corrosive media and high-temperature applications. Transducer apparatus 100 can be formed via a ceramic-on-metal technology adapted for use as a pressure sensor design that can be constructed at a low-cost. Processes that are utilized for the formation transducer apparatus 100 include molecular bonding of ceramic to a metal diaphragm, such as, for example, metal diaphragm 119, followed thereafter by welding of the metal diaphragm (i.e., metal diaphragm sensor) to the input pressure port. The ceramic-on-metal design provides high-accuracy and stability over an operating temperature range of approximately 40° C. to 150° C.
Ceramic material can be molecularly bonded to the metal diaphragm utilizing an ATF (Advanced Thick Film) process. The metal diaphragm is therefore formed as a ceramic coated article having a metal core (i.e., the metal of the metal diaphragm) and having on at least a portion of the surface of the metal core a coating of a ceramic. The ceramic can be, for example, a glass ceramic, but the use of glass ceramics is not considered a limiting feature of the present invention. Glass ceramic is presented herein only as an example in which the invention can be embodied via the ATF process.
A glass ceramic coating can be based on its oxide content and on the total weight of the coating, comprising, for example, (a) from about 8 to about 26% by weight of magnesium oxide (MgO); (b) from about 10 to about 49% by weight of aluminum oxide (Al2O3); and (c) from about 42 to about 68% by weight of silicon oxide (SiO2). Ceramic/glasses adapted for use with the transducer apparatus 100 described herein, generally possess high temperature re-firing capabilities (e.g., 850° C.), and are air fireable. Moreover, ceramic coated article can exhibit a composite thermal coefficient of expansion which is optimum for use in electronic devices, and which can exhibit a low dielectric constant which allows for use with high frequency circuits and allows for greater applicability in electronic application.
Furthermore, the ceramic/glasses utilized via the ATF process thereof can exhibit strong adhesion to the metal substrate after firing and are very resistant to thermal stress. This avoids breakdown of the devices formed from the ceramic coated article of this invention when such articles are exposed to high temperatures normally encountered in the operation of electronic devices. This resistance to thermal stress is indeed surprising in view of the relatively large difference in the thermal coefficient of expansion of the metal substrate and the ceramic glass, and the prior teachings that the metal and coating coefficients of expansion must be matched to produce good adhesion.
The glass/ceramic coated article thus generally comprises a metal core and possesses on at least a portion of the surface of the metal core a coating of a glass ceramic. A general example of the ATF involves: (a) heating a metal substrate in the presence of oxygen at a first temperature for a time sufficient to form any amount of an oxide layer on the surfaces of the substrate; and (b) applying to all or a portion of the surfaces of the substrate a suspension comprising one or more organic solvents, one or more heat degradable polymeric binders and a calcined mixture of finely divided non-conductive materials comprising (i) from about 8 to about 26% by weight of MgO; (ii) from about 10 to about 49% by weight of Al2O2 and (iii) from about 42 to about 68% by weight of SiO2.
Such an ATF process additionally can include (c) heating the coated/metal substrate combination of step (b) at a second temperature for a time sufficient to remove substantially all of the solvents from the applied suspension; and (d) heating the coated/metal substrate combination of step (c) at a third temperature for a time sufficient to degrade substantially all of the binders in the applied suspension; (c) heating the coated/metal substrate combination of step (d) at a fourth temperature for a time sufficient to sinter the non-conductive material to form a device comprising a metal substrate having a predetermined pattern of glass/ceramic material bonded to one or more surfaces thereof.
The material can generally comprise (on an oxide basis): (i) from about 8 to about 26% by weight of MgO; (ii) from about 10 to about 49% by weight of Al2O3; and (iii) from about 42 to about 68% by weight of Si O2; (f) heat treating the device at a fifth temperature for a time sufficient to re-crystallize any residual glass contained in the material to any extent.
The ATF process provides for greater selectivity in the application of the glass/ceramic materials to specific sites on a substrate which provides for greater freedom in the manufacture of devices such as the transducer apparatus 100. After processing, in accordance with embodiments disclosed herein, the coating can contain crystallized glass/ceramic, which strongly adheres to the metal core and can be suitable as a substrate for processed induced components. An example of an ATF process is disclosed in U.S. Pat. No. 4,794,048 entitled, “Ceramic Coated Metal Substrates for Electronic Applications,” which issued to Oboodi et al on Dec. 28, 1988, and which is incorporated herein by reference. Another example of an ATF process is disclosed in U.S. Pat. No. 4,997,698 entitled “Ceramic Coated Metal Substrates for Electronic Applications,” which issued to Oboodi et al on Mar. 5, 1991, and which is incorporated herein by reference.
The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention. Those skilled in the art, however, will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. Other variations and modifications of the present invention will be apparent to those of skill in the art, and it is the intent of the appended claims that such variations and modifications be covered.
The description as set forth is not intended to be exhaustive or to limit the scope of the invention. Many modifications and variations are possible in light of the above teaching without departing from the scope of the following claims. It is contemplated that the use of the present invention can involve components having different characteristics. It is intended that the scope of the present invention be defined by the claims appended hereto, giving full cognizance to equivalents in all respects.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4136603 *||Nov 14, 1977||Jan 30, 1979||The Foxboro Company||Diaphragm assembly|
|US4794048||May 4, 1987||Dec 27, 1988||Allied-Signal Inc.||Ceramic coated metal substrates for electronic applications|
|US4974117||Jan 31, 1990||Nov 27, 1990||Kavlico Corporation||Dual diaphragm capacitive differential pressure transducer|
|US4997698||Jun 23, 1989||Mar 5, 1991||Allied-Signal, Inc.||Ceramic coated metal substrates for electronic applications|
|US5499158||Nov 14, 1994||Mar 12, 1996||Texas Instruments Incorporated||Pressure transducer apparatus with monolithic body of ceramic material|
|US5525280||Apr 7, 1994||Jun 11, 1996||Texas Instruments Incorporated||Method of making a pressure transducer apparatus|
|US5544399||Feb 17, 1995||Aug 13, 1996||Texas Instruments Incorporated||Method for making a pressure transducer|
|US6091022||Dec 17, 1998||Jul 18, 2000||Honeywell Inc.||High pressure header for a semiconductor pressure transducer|
|US6209398||Sep 18, 1998||Apr 3, 2001||Texas Instruments Incorporated||Fluid pressure transducer apparatus and method for assembling|
|US6528340||Jan 3, 2001||Mar 4, 2003||Honeywell International Inc.||Pressure transducer with composite diaphragm|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7243541||Mar 30, 2006||Jul 17, 2007||Honeywell International Inc.||Combi-sensor for measuring multiple measurands in a common package|
|US7266999||Jan 30, 2006||Sep 11, 2007||Honeywell International Inc.||Thick film technology based ultra high pressure sensor utilizing integral port and diaphragm construction|
|US7360438 *||Feb 8, 2006||Apr 22, 2008||Honeywell International Inc.||Advanced thick film load cell|
|US7493823||Jun 16, 2006||Feb 24, 2009||Honeywell International Inc.||Pressure transducer with differential amplifier|
|US7513164 *||Dec 18, 2007||Apr 7, 2009||Honeywell International Inc.||Single diaphragm ATF differential pressure transducer|
|US7712347||Aug 29, 2007||May 11, 2010||Honeywell International Inc.||Self diagnostic measurement method to detect microbridge null drift and performance|
|US7814798||Sep 17, 2008||Oct 19, 2010||P I Components Corporation||Diaphragm structure and method of manufacturing a diaphragm structure|
|US7832269||Jun 22, 2007||Nov 16, 2010||Honeywell International Inc.||Packaging multiple measurands into a combinational sensor system using elastomeric seals|
|US8175835||May 17, 2006||May 8, 2012||Honeywell International Inc.||Flow sensor with conditioning-coefficient memory|
|US8459125||Aug 1, 2011||Jun 11, 2013||Honeywell International Inc.||Pressure sensor assembly|
|US8534130||Aug 1, 2011||Sep 17, 2013||Honeywell International Inc.||Joint between a pressure sensor and a pressure port of a sensor assembly|
|US8616065||Aug 2, 2011||Dec 31, 2013||Honeywell International Inc.||Pressure sensor|
|US8656772||Oct 14, 2011||Feb 25, 2014||Honeywell International Inc.||Flow sensor with pressure output signal|
|US8656786||Aug 1, 2011||Feb 25, 2014||Honeywell International Inc.||Interchangeable pressure sensor assembly and methods of assembly|
|US8671753||Aug 1, 2011||Mar 18, 2014||Honeywell International Inc.||Cable harness for a sensor|
|US8695417||Jan 31, 2011||Apr 15, 2014||Honeywell International Inc.||Flow sensor with enhanced flow range capability|
|US8718981||May 9, 2011||May 6, 2014||Honeywell International Inc.||Modular sensor assembly including removable sensing module|
|US8817483||Aug 1, 2011||Aug 26, 2014||Honeywell International Inc.||Connector assembly for a sensor|
|US8934263||Aug 1, 2011||Jan 13, 2015||Honeywell International Inc.||Protective cover for pressure sensor assemblies|
|US9003897||May 10, 2012||Apr 14, 2015||Honeywell International Inc.||Temperature compensated force sensor|
|US9052217||Nov 9, 2012||Jun 9, 2015||Honeywell International Inc.||Variable scale sensor|
|US9658126||Feb 3, 2014||May 23, 2017||Honeywell International Inc.||Interchangeable pressure sensor assembly and methods of assembly|
|US20070186661 *||Jan 30, 2006||Aug 16, 2007||Honeywell International Inc.||Thick film technology based ultra high pressure sensor utilizing integral port and diaphragm construction|
|US20070271070 *||May 17, 2006||Nov 22, 2007||Honeywell International Inc.||Flow sensor with conditioning-coefficient memory|
|US20070289389 *||Jun 16, 2006||Dec 20, 2007||Honeywell International Inc.||Pressure transducer with differential amplifier|
|US20080314118 *||Jun 22, 2007||Dec 25, 2008||Honeywell International Inc.||Packaging multiple measurands into a combinational sensor system using elastomeric seals|
|US20090277434 *||May 8, 2008||Nov 12, 2009||Ford Global Technologies, Llc||Control strategy for multi-stroke engine system|
|US20100064816 *||Sep 17, 2008||Mar 18, 2010||Dario Filippi||Diaphragm structure and method of manufacturing a diaphragm structure|
|International Classification||G01L19/14, G01L9/00|
|Feb 24, 2009||FPAY||Fee payment|
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|Feb 25, 2013||FPAY||Fee payment|
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|Feb 24, 2017||FPAY||Fee payment|
Year of fee payment: 12